| Message ID | 20171127111629.1682286-1-arnd@arndb.de |
|---|---|
| State | Superseded |
| Headers | show |
| Series | vmwgfx: use monotonic event timestamps | expand |
On Wed, Dec 13, 2017 at 9:56 PM, Sinclair Yeh <syeh@vmware.com> wrote: > This looks okay to me. Although we should change eaction->tv_* type > to 64-bit as well. I thought about it but it would add significant complication without real gain, as the eaction->tv_* pointers point into uapi structures (drm_vmw_event_fence and drm_event_vblank) that are defined as 32-bit times and cannot be changed. Changing the temporary pointer to 64 bit would require adding a temporary variable to point to and then doing the truncation in the callers. With monotonic times, we know that 32-bit times are sufficient, they are good for 136 years after boot (68 years when interpreted as signed). Arnd
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c b/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c index d6b1c509ae01..55214d0da66e 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c @@ -897,11 +897,12 @@ static void vmw_event_fence_action_seq_passed(struct vmw_fence_action *action) spin_lock_irq(&dev->event_lock); if (likely(eaction->tv_sec != NULL)) { - struct timeval tv; + struct timespec64 ts; - do_gettimeofday(&tv); - *eaction->tv_sec = tv.tv_sec; - *eaction->tv_usec = tv.tv_usec; + ktime_get_ts64(&ts); + /* monotonic time, so no y2038 overflow */ + *eaction->tv_sec = ts.tv_sec; + *eaction->tv_usec = ts.tv_nsec / NSEC_PER_USEC; } drm_send_event_locked(dev, eaction->event);
DRM_VMW_EVENT_FENCE_SIGNALED (struct drm_vmw_event_fence) and DRM_EVENT_VBLANK (struct drm_event_vblank) pass timestamps in 32-bit seconds/microseconds format. As of commit c61eef726a78 ("drm: add support for monotonic vblank timestamps"), other DRM drivers use monotonic times for drm_event_vblank, but vmwgfx still uses CLOCK_REALTIME for both events, which suffers from the y2038/y2106 overflow as well as time jumps. For consistency, this changes vmwgfx to use ktime_get_ts64 as well, which solves those problems and avoids the deprecated do_gettimeofday() function. This should be transparent to to user space, as long as it doesn't compare the time against the result of gettimeofday(). Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- drivers/gpu/drm/vmwgfx/vmwgfx_fence.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) -- 2.9.0